In mechanically controlled compression ignition engines, the engine's physical structure often determines its operating characteristics. It is, therefore, difficult to vary the operating characteristics without varying the physical structure of the engine. With the advent of electronically controlled engines, the operating characteristics of the engine, and of the vehicle in which the engine is installed, could be easily changed by programming different parameters into the electronic controller.
When electronic controllers were first introduced on compression ignition engines, it was typical for all parameters to be preprogrammed into the controller at the factory. One set of parameters that typically are programmed at the factory are fuel limit data, which are stored as a function of engine speed and determine the rated horsepower output of the engine. Other factors that may be programmed into the engine may include fuel injection timing, engine speed limits and power derate strategies, among others. As electronic engine control became more well accepted and microprocessors and other control components became more robust, the controller was able to control other characteristics such as maximum vehicle speed, among others. In some electronically controlled engines, the customer is permitted to program some parameter values to most closely tailor the engine operating characteristics to her desired application.
For example, if the engine was purchased by a fleet, the fleet manager may want to limit the maximum speed at which the vehicle operator can drive to thereby improve fuel mileage. To provide the greatest flexibility and allow for differences in specific applications, the fleet manager would be permitted to program the maximum vehicle speed value within a range of permissible maximum vehicle speed values. Similarly, the fleet manager or end user might be permitted to program other operating conditions into the electronic controller.
Vehicle operators sometimes do not like the programmed limits and other values programmed by the fleet manager into the controller. And, in some instances vehicle operators or someone else might reprogram the customer selectable values to values other than those originally selected by the fleet manager. In those cases it would be possible for the vehicle operator to defeat some of the objectives of the fleet manager (e.g., to conserve fuel by limiting the maximum vehicle speed.) In prior art compression ignition engines, the fleet manager cannot tell that these values have been changed without driving the vehicle and guessing based on engine and vehicle performance.
It would be desirable to have an electronically controlled engine that could download a report to the fleet manager or other appropriate responsible party that would indicate to the fleet manager that the customer controlled parameters had been changed to values other than those that were originally programmed.